CO should have a shorter cooldown, mp returns 5 or 10% depends on its cooldown, and some enhancements on its potency as well if its cooldown stays that long.

My suggestion

Cooldown stays the same on 120secs, than double potency and give 10% mp return.
Cooldown on 60secs, give 5% mp returns, can stand the weak potency since it has a shorter cd.

It would be good to have the stun back as well.